DESCRIPTION: (from the applicant's abstract). The hypothesis of this proposal is that the plasma and extracellular matrix protein vitronectin (VN) contributes to the extensive and accelerated vascular disease suffered by diabetics. Unmodified VN can enhanced thrombosis and atherogenesis by binding to and stabilizing plasminogen activator inhibitor-1 (PAI-I), by promoting smooth muscle cell (SMC) haptotaxis, and by prolonging the activity of thrombin. VN may also regulate angiogenesis, since it binds both angiostatin (an inhibitor) and hepatocyte growth factor (HGF, a promoter for angiogenesis). Recent studies have shown that VN is glycated in a animal model of diabetes, and that in vitro-glycated VN has shown altered functions (e.g., increased PAI-1 binding). We hypothesize that VN may contribute to the accelerated progression of vascular disease in diabetics via: (1) enhanced deposition into the vessel wall, (2) enhanced expression in the vessel wall, and/or (3) enhanced atherogenic functions secondary to protein glycation. In this proposal, we will: (1) develop an ELISA assay to compare the levels of glycated VN in diabetics and non-diabetics, (2) compare the extent of VN antigen (using immunohistochemistry) and expression (using RT-PCR) in the coronary arteries of diabetics and non-diabetics and (3) determine functional consequences of the glycation of VN that are relevant to vascular disease. The functional effects that we will study are (A) the ability of glycated VN to induce TGF-b 1 secretion, (B) the binding of glycated VN to PAI-1, (C) the ability of glycated VN to promote SMC migration, and (D) the binding of glycated VN to angiostatin and to HGF. If VN does contribute to the pathogenesis of diabetic vascular disease, than an animal lacking VN should be relatively protected from this complication. We will directly test this hypothesis by creating a hyperglycemic state in VN null mice and in a control strain. These studies could elucidate novel strategies to prevent the vascular manifestation of diabetes.